US2295284A - Tandem rolling mill - Google Patents

Description

Sept. 8,1942. J. P. MQCA'FFREY' ET AL 2,295,284

TANDEM ROLLING MILL 3 Sheets-Sheet 1 Filed Oct. 13, 1958 I [MA/T0225.

NHN N ATTURNEX J. P. M CAF'FREY ETAL 2,295,284

TANDEM ROLLING MILL Sept. 8, 1942.

Filed Oct. 13, 1938 Y s Sheets-Sheet 3 Patented Sept. 8, 1942 UNlTED STATES PATENT OFFICE TANDEM ROLLING MILL Joseph P. McCafirey, Carnegie, and Sylvester J. Kern, Dormont, Pa.

Application October 13, 1938, Serial No. 234,802

16 Claims.

This invention relates to improvements in the operation and control of tandem rolling mills or the like, and more particularly to automatically operable mechanism actuated and controlled by the passage of a material through the mill.

In present tandem mill practice, the material or strip is reduced by passage through a succession of roll stands until the desired thickness or gauge is produced, each roll stand usually being driven by a separate motor, and the speeds of such motors being manually controlled by the roller or operator.

In order to operate such mills at high speed while at the same time maintaining the proper tension on the strip or other material therebetween, it has been found expedient to produce a slack in the material between each pair of roll stands, which slack is known as a loop.

The present invention contemplates automatically forming and utilizing a loop or loops in the strip for maintaining proper relative speeds of the roll stands in tandem mill operation, to insure uniformity of product and to prevent undesirable elongation as well as preventing lapping or cobbling of the strip.

By means of our invention, the control and operation of the mill is governed by the passage of the material through the successive roll stands, and contemplates control means adapted to be set in operation by the entering end of the strip and released by the tail end thereof. Hence, our invention is readily applicable to hot mill operation where the metal is not treated in a continuous strip but rather in a disconnected series of individual strips.

Our invention provides an adequate and completely automatic control and regulation of the mill for a predetermined safe looping maximum satisfactory for normal working conditions. However, in the event that such safe maximum loop is exceeded, as through an excessive improper draft occurring at a roll stand, we provide safety control means which automatically acts to bring the entire control system and mill operation back to normal operating conditions, preventing lapping or cobbling of the strip and the shutdowns, delays and expense attendant there- Additional objects and advantages will become apparent from the following description taken in connection with the accompanying drawings,

wherein:

Fig. 1 is a schematic view of a tandem rolling mill constructed in the manner of our invention,

showing the control means thereof in starting position;

Fig. 2, a plan view of one of the loopers or 10- cators and its clutch-driven motor controller;

Fig. 3, an enlarged plan view of the clutch mechanism of Fig. 2; and

Fig. 4, a view similar to Fig. 1, showing the mill in operation, and. illustrating the safety control feature of our invention.

Referring to the drawings, l, 2 and 3 illustrate a series of roll stands each comprising suitable rolls, housings, etc. as is well known in the art, said stands being arranged in tandem and the rolls thereof separately driven in the usual manner by motors M1, M2 and M3 respectively, through connecting drive shafts indicated at 4. It will be understood that there may be any suitable number of roll stands, three being shown merely by way of illustration.

Centrally located between adjacent roll stands of the mill is provided a looper or locator device, two being shown and designated generally as L1 and L2, said loopers including a transverse shaft 5 rotatable in suitable bearings 6, and Outriggers or side arms I secured to and rotatable with the shaft. An idler roll 8 is carried transversely between the free ends of the arms 1, and a flat table portion or bed 9 extends between said arms.

The locators or loopers L1 and L2 are mounted in normal or retracted position in the horizontal plane of the mill table or bed proper B. It designates abutments or stops engageable by the free ends of the looper arms I for alining the loopers in retracted horizontal position.

Centrally of and pivotally secured to crossmembers I l below the locators or loopers L1 and L2 are plungers [2 of hydraulic cylinders I3, the latter having pivotal anchorages [4 with a suitable foundation or the like. The lower ends of the cylinders l3 are connected by flexible tubing I5 and pipes IS with the lower ends of cylinders I! of accumulators A, which accumulators include weighted plungers IS. The accumulator loadings are adjustable as by weights H), which weights may be varied as to size and number, and are carried by and movable with the plungers l8 to exert a selected static pressure upon a body of oil or other fluid between the plungers l8 and I2 for elevating the locators L1 and L2 about their shafts 5.

Similarly secured to cross-members 21] of the loopers or locators are pistons 2| of air cylinders 22, the latter being pivotally anchored at 24 by their lower ends. The upper ends of cylinders 22 are connected by flexible tubing 25 and --by conduit 55.

pipes 26 with adjustable valves 21. When compressed air is supplied to cylinders 22, pistons 2| thereof serve to retract the locators or loopers L1 and L2 against the hydraulic lifting pressure of the accumulators A, and secure said locators against their abutments l0.

Locator shafts 5 extend laterally at one side of the mill and are connected through clutches C with rotary drum controllers D2 and D3, of a well known type, for controlling the speeds of the motors M2 and M3 respectively, as hereinafter set forth.

Clutches C comprise coactin friction parts, including members 28 rotatable with the locator shafts 5 and engageable Withmembers-ZQ rotatable with jack shafts 30 in turn connected with gear drives G, the latter also being connected with the shafts 3! of controllers D2-and-D3. The gear drives G may be of any suitable construction, and serve to amplify the rotation of locator shafts 5 so-as toimpart one complete revolution of the controller arms 32 on shafts 3! for the maximum travel of thelocators.

Clutches C'are designed to be normally engaged by means of sprirlgs33, andmemb'ers 29 thereof are provided with disengaging means including movablecollars or 'yokes 34 connected by-a suitable -linkage 35 with pisto'ns 35-ofaircylinders 3'! operated by adjustable valves 38.

The electric motors :M1,'M2 and "Ms' maybe of any' suitable' type" and are here-shown for pur "poses of: i'llu'strationas compound motors.

Motor Mii is connected witha high'voltage line 39 by conduits '40 and 'has a manual speed control 4| suitably"'ccnnecte'd in circuit therewith. Motors M2 and M3 are likewise connected with the power 'line39by conduits 42 "and 43, and are'suitably connected for"speed adjustment thereof with the controllers D2 and D3 "by conduits 44 "and 45 respectively.

*45 designates a relay-connected in the circuit ofmotorM -which relay isdesigned to'close upon an increa-se of amperage in: said motor, as when the "strip S enters the roll'stand I. The closing of relay45 connects a conduit with a low volt- --age source ia'through 'saidrelay and a conduit 49, c'on'duit4l being connected-With asecond relay-50, which latter relay is connected with and designed toclose upon increased amperage in motorMz of'roll stand 2.

Relay 59 shown as having tWdseparate contact plates,one of which is designed'to make contact between conduit-4'! and a conduit 5|, the

latter having a solenoid 52 'in' series therewith and connecting with a contact-arm 53 on member-29 of clutch C of-the locator or looper L1. A

coacting 'contact'arm 54 on member 28 of-said clutch is connected with the power supply48 as 56 designates a solenoid connected-between thepower'source 43 and conduit 5!.

The other contact plate of relay fiii connects the supply.-source-48,- through a conduit 51, with a conduit-58, whereby the relay circuit is electrified and extended-toe. third relay-59 connected in the circuit of motor M; of roll stand 3.

Relay SB-islike-relay 5i), and serves to connect a conduitefiil with the supply source '28 through conduit iitand relay 5i conduit 55 having a sole amid 3! therein and connectinga contact arm 62 on member 29 of the clutch C of'locator L2. Contactarm'BS of member 28 of said clutch is connected=- with the-:powersupplydfi as by a conduit E4. 65 designates a solenoid connected between "the-power line wand conduit Bil.

-The--remaining contact plateof relay 59- connects the supply source 48, through a conduit 66, with a conduit 61, by which latter conduit the relay circuit may be extended and connected in a similar manner with the motor and controls of an additional roll stand or stands, not shown.

The solenoids described are utilized to manipulate the air valves 21 or 38 as hereinafter set forth, said valves being of a character capable of delivering air from a supply pipe 68 to their respective cylinders in one position of adjustment, and then exhausting said delivered air to the atmosphere in another position of the valves.

Springs 69 may be employed for returning the 53' and 59open.

The controllers 4!, D2 and D3 are initially set with locators L1 and L2 in-said lowered position to impartproper initial speeds to their respective motors. For example, in accordance with standard' practice,the said initial settings may be so adjusted so that each roll stand is driven at an increased speed over its preceding roll stand. Also, the proper drafts or adjustments are applied to the rolls.

The increased load uponmotor-M1 as the strip S enters the rolls of stand I, will actuate the relay 2S, thereby-energizing conduit-41 leading to thesecond relay 56. Strip S passes over the mill table B and overthe locator or'looper L1, and upon entering roll stand 2, causes an increase in amperage in motor M2 to close relay 5!].

As relay 50 closes, a circuit is completed with the power source-48 through conduits 49, relay is, conduit 41,.relay50, conduit 5|, clutch contacts5-3, 54, and conduit 55, thereby energizing solenoids 52 and 56. Solenoid 52 moves its valve 38, cutting off the .air supply from line 68, and exhausting cylinder 37- to the atmosphere, whereupon spring 33 engages the clutch C and connects controller D2 with its locator or looper L1.

Solenoid moves its valve 21 to cut off the air supply and exhausts cylinder 22 of locator L1 to the atmosphere, whereupon plunger l2 of oil cylinder 8-3 moves the said locator upward into engagement with the strip S.

Similarly, as the strip S enters roll stand 3, the increased load upon its motor M3 will close relay 59 completing a circuit with power source as through conduit 57, relay 5!], conduit 58, relay 555, conduit 6!], clutch contacts 62, 63, and conduit 54, thereby energizing solenoids GI and 65. The action of said solenoids is as before, to permit the engagement of the clutch C of locator L2 and release said locator for elevation thereof by its oil plunger and the accumulator pressure. It will therefore be seen that the entrance of the strip in a roll stand is utilized to release a locator associated therewith for controlling movement as hereinafter set forth, and further, that the same relay circuit and associated mechanism may be continued for each additional roll stand employed.

The relative positions of the various elements of the control system while the mill is in operation are illustrated in Fig. 4.

The static load on the accumulators A may be adjusted for proper pressure of the locators or loopers L1 and L2 upon the strip S, whereby said strip is upwardly flexed between the respective roll stands as indicated in the drawings, there being a predetermined maximum upward travel of said locators as by limit of movement of the pistons 2| of the air cylinders 22.

Between this upper maximum and the horizontal or retracted positions of the locators, which may be called the range of the locators, the said locators follow any variation in flexing or looping of the strip and exert a constant upward pressure thereon, which pressure opposes the downward force of the strip portion between the pairs of roll stands.

The motor controllers D2 and D3 vary the speeds of their respective motors within the range of movement of the locators, and are so disposed that they eiiect an increase in motor speed directly proportional to the rise or upward travel of the locators.

As to each pair of roll stands, a locator and its associated controller operate to control the speed of the rolls of the receiving stand, whereby for example, upon an upward movement of a locator or looper, the speed of the receiving rolls increases, thereby counteracting the upward tendency of the strip and decreasing the loop. Hence, the strip and locator fluctuates until, under normal working conditions, the strip will run smoothly and uniformly through the mill.

In practice, it may be necessary to adjust the over-all speed of the mill in accordance with the observed operation thereof. This adjustment may be accomplished by changing the speed of motor M1 of roll stand I, as by controller 4|, which change is reflected and progressively continued throughout the entire mill.

For example, assuming the mill to be operating at too great a speed, a reduction in the speed of 'the rolls of stand I will cause the loop between stands I and 2 to flatten, thereby lowering the speed of the motor M2 of roll stand 2.

A similar reduction will be efiected at each successive roll stand, the speed of the rolls of each stand being adjusted in accordance with the change occurring at the roll stand delivering the strip to it, until the speed of the entire mill composed of a series of stands, is automatically reduced.

Similarly, when variations occur, as by a variation in hardness of the material or strip, or a sudden change in roll adjustment, etc., the change of speed produced thereby will progress throughout the mill. As the source of variation either corrects itself, as by a harder portion of metal passing out of the mill, or such variation is corrected by draft adjustment of the rolls, etc., the entire mill again builds up or down to its normal running speed, as the case may be.

As the tail end of the strip S leaves roll stand 1, the amperage of motor M1 immediately decreases, thereby opening relay 56 and breaking the circuit in conduits M, 5!, and 55, and deenergizing solenoids 52 and 5%. Air valves 2'! and. 38 return-by springs 89 to position admitting air from pipe 68 to cylinders 31 and 22 of the mechanism of locator or looper L1. Piston 35 and its linkage 35 opens the clutch C of said locator, and piston 2| lowers said locator against the pressure of its accumulator A.

Due to the immediate disengagement of the clutch C of locator L1, the controller D2 will not be moved by the initial retraction of the locator,

until after the tail end of the strip S leaves roll stand 2.

For the purpose of timing the reduction of speed of the roll stand 2, the clutch C of locator L1 is provided with an adjustable abutment I0. Said abutment is like contact arms 53 and 54, and is secured to clutch member 29 by T-bolt ll in a suitable peripheral slot l2. Contact arm 53 of member 29 is likewise secured in said slot by a similar bolt 13. Contact arms 53 and 54 and abutment or stop 10 extend axially of the clutch as clearly shown in Fig. 3.

By reason of the peripheral slot 12, the radial spacing or are between contact 53 and abutment I0 may be adjusted, so that the interval from the time the clutch opens, as above described, until the tail end of the strip leaves the roll stand 2, will coincide with the rotation of clutch member 28 by the retracting or lowering movement of the locator, whereupon contact arm 54 moves from engagement with contact 53 and engages abutment 19.

Following the engagement of contact arm 54 and abutment 10 of the clutch coincidently as the tail end of strip S leaves roll stand 2, the continued lowering of locator L1 will move member 29 of said clutch to correspondingly adjust the controller D2 to slightly lower the speed of motor As the tail end of strip S leaves roll stand 2, the decreased amperage in motor M2 causes the relay 50 to open, whereupon the locator L2 is retracted and its clutch C disengaged as hereinbefore described, the speed of roll stand 3 not being decreased until the strip leaves said stand, due to the clutch mechanism. Since the action of the control is identical with that described it is deemed unnecessary to repeat the same in detail.

For further adjustment of the automatic control just described, we provide adjustable valves 14 controlling the flow of air from the supply 68 to the valves 2'! and to locator cylinders 22, whereby the interval of retraction of the locators may be accurately regulated with reference to the passage of the strip through the mill.

Hence, as the tail end of the strip leaves the mill, the latter is automatically prepared to receive another strip, with the speed of roll stand 4 brought back to its original orset speed, and all other roll stands having been reduced in speed slightly below that attained during the preceding rolling operation.

As a new strip is entered in roll stand i and passes to roll stand 2, the relays 56 and 52 will close as before. However, since clutch contacts 53 and 54 are separated as above described, the clutch of locator L1 remains temporarily disengaged. The closing of said relays completes a circuit through the solenoid 56, whereupon the valve 2'! releases the pressure in air cylinder 22, and the locator L1 is raised by the accumulator pressure.

As the locator L1 reaches its range of movement, as determined by the previous rolling oper-. ation, it engages the strip and the contact arm 54 of the clutch member 28 engages contact arm 53 of clutch member 29, thereby completing the circuit through solenoid 52 and closing the clutch for locating control operation as before. Similarly, the closing of relay 59 effects a similar raising of locator L2, including a closing of the clutch contacts of said locator, etc.

It will therefore be seen that our invention provides a complete automatic control for tandem particularly suitable to hot mill operation.

Although the maximum travel'of the locators L1 and L2 is adequate for the looping or slack normally encountered in rolling practice, it may be that uncontrollable ccn'ditions may cause the strip to exceed said maximum. Should the strip thus exceed the range of the control, lapping or cobbling might occur, causing damage, shutdowns, expense, and even endanger the mill operators. We have provided a safety control for preventing these undesirable conditions, which control is set in motion by the excessive looping of the strip and acts in conjunction with the main control system.

Referring to Fig. 4, the strip S is shown looped to the maximum travel of the locators L1 and L2, the said maximum being predetermined by the travel of pistons 2| in air cylinders 22. Should the strip loop upwardly beyond this maximum, it will engage pivoted switches E1 or E2 above the locators L1 and L2 respectively, to properly retard the mill.

In connection with the use of the safety control, we prefer to employ a drum type controller D1 for the motor M1 of roll stand I, suitably connected in the circuit of said motor as by conduits 75. An adjustable arm 16 is rotatable with the shaft of the controller through an intervening gear drive G, whereby a relatively small arc of movement of the arm eiiects a complete rotation of the controller D1.

The arm 15 is provided with a hydraulic cylinder I3 serviced by an accumulator A to exert a proper upward pressure on the arm, and also has a retracting air cylinder 22 connected with an adjustable valve 27. A solenoid H is energized from the power source All to normally move said valve to open cylinder 22' to the atmosphere, whereby the plunger of oil cylinder l3 elevates the arm '36 against an adjustable stop or screw 13 whereby the speed of motor M1 may be regulated and maintained normally constant.

Assuming the over-looping to occur between the roll stands I and 2, the switch E1 will be thereby moved to close contacts 19 of said switch, making a circuit with power source 48 and opening a relay 80 in the circuit of solenoid 11. The interruption of the circuit in solenoid 11 permits air valve 27' to be moved by its spring 69' to connect the air cylinder 22 with the air supply, whereby the piston in said cylinder retracts the arm 16, moving controller D1 to retard the speed of motor M1. The reduction in speed of the rolls of stand I permits the rolls of stand 2 to reduce the excess loop until the contents 19 open, and arm 16 is again returned to normal speed adjustment postion against stop 18 by the prezsure of the accumulator A.

8! designates a second or lower adjustable stop for the contact arm 16, whereby the amount of decrease in speed of the motor M1 necessitated by said over-looping may be regulated.

Should the excess occur between roll stands 2 and 3, the switch E2 will be actuated to close contacts 82, making a circuit with source 48 and opening a relay 83 in the circuit of solenoid 56. As the circuit through solenoid 56 is interrupted, air valve 2! is moved to supply air to cylinder 22 of locator L1, whereby said locatoris retracted and correspondingly moves controller D2 to decrease the speed of motor M2 of roll stand 2, thus permitting roll stand 3 to reduce the excess in the strip. A similar safety switch mechanism mill operation governed by the passage of the strip therethrough, and provides control meansmay be" employed in conjunction with a lo'cator or looper betw'eeneach pair of roll stands throughout=the mill.

It will be seen that the overall speed of the mill may be regulated as before, by adjustment of'the stop 18.

While we have not shown coiling devices associated with the tandem rolling mill, such devices, it is well known, are sometimes employed and it is evident that our invention may be' utilized in connection with such devices for controllingthe speeds of the coiling devices. In the appended claims, the expression tandem rolling mills and thelike is intended to cover coiling devices.

We claim:

1. In a tandem rolling mill or the like, a delivering roll stand and a receiving roll stand immediately following said delivery stand, motors for driving the rolls of said stands, means for controlling the speed of the motor of the receiving stand effective through the load imposed on such motor, a loop'er device located between the stands, means operable through the presence of material entered in the rolls of both stands for effecting an upward pressure contact of the looper against the material and exerting pressure thereon'so long as the material is enteredin the rolls of both-stands, and positively acting means directly connected with the looper and actuated immediately bythe discharge of the end of the material from the delivery roll stand for returning the looper to its lowermost" position.

2. In a tandem rolling mill or the like, a d livering roll stand and a receiving roll stand immediately following said delivery stand, motors for driving the rolls of said stands, means for controlling the speed of the motor of there'ceiving stand efiective through the load imposed on such motor, a looper device located between the stands, means operablethrough the presence of material entered in the rolls of both stands for eifecting an upward pressure contact of the looper against the material and exerting pressure thereon so long as the material is entered in the rolls of both stands, and positively acting means including a column of air acting against another column of fluid and actuatedimmediately by the decreased load on the motor of the delivering rolls due to the discharge of material therefrom for retracting the looper.

3. In a tandem rolling mill or the like, a delivering roll stand and a receiving roll stand immediately following said delivery stand, motors for driving the rolls of said stands, a movable looper between the stands for exerting a tension on a material being rolled, a controller for the receiving roll stand motor actuated by movement of the looper, means controlling the looping movement of said looper, means in the circuit of the receiving roll stand motor actuating the looper control means to provide continuous looping travel of the looper during the rolling of the material in both of said stands, and means in the circuit of the delivering roll stand motor actuating the looper control means to retract the looper upon the discharge of the end of the materi'al frcm the delivering roll stand.

4. In a tandem rolling mill or the like, a delivering roll stand and a receiving roll stand immediately following said delivery stand, motors for driving the rolls of said stands, a movable looper between the stands for exciting a tension on a material being rolled, a controller for the receiving roll stand motor actuated by movement of the looper, means controlling the looping movement of said looper, means in the circuit of the receiving roll stand motor actuating the looper control means to provide continuous looping travel of the looper during the rolling of the material in both of said stands, means in the circuit of the delivering roll stand motor actuating the looper control means to retract the looper upon the discharge of the end of the material from the delivering roll stand, and means preventing a reduction in speed of the receiving stand motor by its controller during the retraction of the looper until the end of the material is discharged from the receiving roll stand.

5. In a tandem rolling mill or the like, a delivering roll stand and a receiving roll stand immediately following said delivery stand, motors for driving the rolls of said stands, a looper device located between the stands, means actuating the looper for continuously exerting a tension on a material being rolled so long as said material is entered in both of said stands, a controller for the receiving roll stand motor actuated by movement of the looper, means automatically operable upon the discharge of the end of the mate rial from the delivering roll stand for retracting the looper, and means preventing movement of the controller during the retraction of the looper to prevent a reduction in speed of the receiving stand motor until the end of the material is discharged from the receiving roll stand.

6. In a tandem rolling mill or the like, a delivering roll stand and a receiving roll stand immediately following said delivery stand, motors for driving the rolls of the stands, means for controlling the speed of the motor of the receiving stand eifective through the load imposed on such motor, a looper device located between the stands for forming a loop in the material being rolled, means for raising the looper initiated upon entrance of the material in the receiving roll stand and continuously operable through the presence of material entered in both of said stands, and positively acting automatically operable means connected with the looper and actuated by decreased load on the motor of the delivery rolls for lowering the looper and maintaining the looper in lowered position operable immediately upon the material leaving the delivering roll stand.

'7. In a tandem rolling mill or the like, a pair of roll stands, motors for driving the rolls of said stands, a movable looper between the stands for exerting a tension on the material being rolled, a controller operable by a predetermined partial movement of the looper to vary the speed of the motor of one roll stand, an automatically operable clutch between the looper and the controller for preventing movement of the controller by the looper during a selected portion of the downward movement of the latter, and adjustable means for subsequently moving the controller to vary the speed of its motor.

8. In a tandem rolling mill or the like, a pair of roll stands, motors for driving the rolls of said stands, a movable looper between the stands for exerting a tension on the material being rolled, a controller for the motor of the second roll stand, a clutch for moving the controller in relation to the movement of the looper to vary the speed of said motor, means operable upon a decreased load on the motor of the first stand due to the termination of rolling at said stand for disengaging said clutch, thereby permitting a movement of the looper without speed adjusting movement of the controller, and adjustable means for subsequently moving the controller to vary the speed of its motor while the clutch is disengaged and during a selected portion of the movement of the looper.

9. In a tandem rolling mill or the like, a pair of roll stands, motors for driving the rolls of said stands, a movable looper between the stands adapted to exert a tension on the material being rolled, means continuously urging the looper against the material between the stands so long as said material is entered in both of said stands, a controller for varying the speed of the motor of the second roll stand in relation to the travel of the looper, an electrically operable clutch for connecting and disconnecting the controller and looper, electrically operable means for controlling the looping movement of said looper, a circuit connecting both of said electrically operable means, a pair of relays controlling said circuit, one of said relays being operable upon an increased load on the second roll stand motor due to rolling at said stand to make said circuit, and the other relay being operable upon a decreased load on the first roll stand motor due to the termination of rolling at said stand to break said circuit, as and for the purpose described.

10. In a tandem rolling mill or the like, a pair of roll stands, motors for driving the rolls of said stands, a movable looper between the stands, means normally urging the looper into tensioning contact with the material being rolled, means for retracting said looper therefrom, electrically operable means for actuating the retracting means, a controller operable by a movement of the looper to vary the speed of the second roll stand motor, electrically operable means for connecting and disconnecting said looper and controller, a relay circuit energizing both of said electrically operable means during rolling at the second roll stand to thereby release the looper and connect the same with the motor controller, said relay circuit being adapted to be deenergized upon the termination of rolling at the first stand to thereby retract the looper and disconnect the motor controller thcrefrom, and means for subsequently moving the controller by the looper during the retraction of the latter from and after the termination of rolling at said second roll stand, as and for the purpose described.

11. In a tandem rolling mill or the like, a pair of roll stands, motors for driving the rolls of said stands, a movable looper between the stands for exerting a tension on the material beingrolled and having a maximum looping travel thereof, a controller operable by a movement of the looper to vary the speed of the motor of one of the roll stands, and means actuated by overlooping of the material beyond the said maximum travel of the looper, for automatically varying the speed of the motor of the other roll stand when the material becomes beyond control of the other or receiving roll stand, as and for the purpose described.

12. In a tandem rolling mill or the like, a pair of roll stands, motors for driving the rolls of said stands, a movable looper between the stands for exerting a tension on the material being rolled and having a predetermined maximum upward looping travel thereof, a controller operable by a movement of the looper to vary the speed of the motor of the second roll stand, and means actuated by the overlooping of the material beyond the said maximum travel of the looper for automatically decreasing the speed of the motor of the first roll stand, as and for the purpose described. 4 4 W 13. In a tandem rolling mill or the lili'e, pair of roll stands, motors for driving therqlls of said stands, means for looping the material being rolled, means for controlling the speeds of the motors of the roll stands, and means operable upon overlooping of the material beyond afpredetermined maximum upward travel of the looping means for decreasing the speed of the motor of the first roll stand while the motor of the second roll stand is running at full speed, as and for the purpose described, v e I 14. In a tandem rolling millor the like, a plurality of roll stands, motors for drivifig the rolls of said stands, means between theroll stands for looping the material being rolled, control "means for varying the speed of the motor of theroll stand immediately following each looper means and operable by the loopers, and safety sjvvitches' between the roll stands operable upon overloopingof the material beyond the maximum looping travel of the loopers for automatically "decreasing the speed of the motor of the roll stand immediately preoeding each safety switch, as and for the purpose Idesjcribed, e v

15. In a tandem rolling mill or the like, a plurality ofroll stands, motors for driving the rolls of said stands, movableloopers betweentheroll stands for exerting a tension on thematerial being rolled, control means ior varying the speed of the motor of the roll' stand immediately following each looper by said looper, electrically ope able 'ihea'n's' for ebrit'rbning the looping movejiiiritsbf the 'lbopefrs, a separate controller for the meter bf the initial roll stand, electrically operable fiie'aiisfor adjustifig's'aid controller, a safety s'with adjacent the "l'o'o er between the initial andscofid r611" Stands and operable :u'pon 'overl'oo'pirig 'of the materiarat fsai'd looper for actuating "the lc'triean 'aperame means to decfeasethei'speed 6f the'motbrof'saiii'initial stand, and a safety swithaajac'ent the 'loope'r between slicdiiig T011 sfafiiis' ioperame upon overlooping er the 'fnat'rial at said looper' for actuating the electrically oprable'fnans "controlling the looper between the roll stands immediately preceding said switch, the'fbyelfc "n "movement of said "ideper to d6rea's'e the s'p'ed of the "motor'of "the 5011 Stand immediately preceding 's'aid switch, as ahdfor' the purpose described. I

1B. In atafiuem follln'g"mill'Drth'e like, a pair ofroll staridsjffibtb'r's' for 'afiving said stands, a lo'operbetvi ieen thestan'ds fofffi'f'min'g' a loop in rial'beihgronemineahsfor rai'singthe lalidby entrance of 'the'mat'er iali'n the second' stan'd; saia looperberng continuously operable vvlfilelilie material is entered in both of said" stands, positively acting means "for rei fr'at ifig the "lbpi "operable immediately upon tlie fl'i-atiial"leaving the first IOll "stand, and adjustable iii'atis' for "regulating the interval of retraction" of saidloopr.

JOS PH P -A F SYLVESTER "J. KERN.

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